Anti-vibration tube support for vertical steam generator



United States Patent [72] inventor Forrest B. Hill, Jr. 3,262,428 7/I966 Romanos 122/34 Chattanooga, Tellllesm FOREIGN PATENTS 1 PP N01791-844 679,058 9/1952 Great Britain 165/67 E ga g:- 33 962,01 1 6/1964Great Britain 165/162 s [73] Assignee Combustion Engineering PrimaryExammer--Albert W. Davls, .l r.

Windsor, Connecticut AnomeysCarlton F. Bryant, Eldon H. Luther, RobertL. a col-paragon f Dehware Olson, John F. Carney, Richard H. Berneike,Edward L.

[54] ANTI-VIBRATION TUBE SUPPORT FOR VERTICAL STEAM GENERATOR l 56]References Cited UNITED STATES PATENTS l.704,097 3/1929 Muhleisen l65/l62X 3,l99.582 8/l965 Vogt etal. 165/69 Kochey, Jr. and Lawrence P.Kessler lateral or vertical flow of vaporizable fluid through the tubebundle.

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BY. v FIG. I I j ATTORNE v PATENTEU min 8 I970 sum 5 0P5 INVENTORFORREST B7 HILL JR. BY Wg f ATTORNE ANTI-VIBRATION TUBESUP PORT FORVERTICAL STEAM GENERATOR BACKGROUND OF THE INVENTION During recent yearsshell and tube type heat, exchangers have been developed to provide ahighly efiicient means for generating vapor. Such vapor generatorsprovide a great amount of heating surface by means of a large number ofsmall diameter tubes disposed in a tube bundle that substantially fillsthe vapor generating chamber formed by the enclosing shell. Vaporgenerators of this type commonly employ tube bundles formed of layers of.U-shaped tubes, the ends of whose legs are secured to a tube sheet atone end of the shell while the horizontally extending bend portionconnecting the legs is 1 disposed uppermost in the chamber. A heatingmedium, such as high-temperature water, vapor, petroleum, or gas, amongothers, is passed through the tubes and gives up a portion of its heatto a vaporizable liquid that is circulated through the chamber about thetubes to emerge from the shell as saturated or superheated vapor.

Because such vapor generators, especially those of high capacity, are ofconsiderable axial length, the tubes that comprise the tube bundlem'ustbe relatively long, thereby rendering them highly susceptible toflow and/or mechanically induced vibrations. Suchvibration is especiallypronounced in the area of the bend portion of the tubes which isthefurthest removed from the points of attachment of the tube ends to thetube sheet. In order, to prevent the deleterious effects of vibration,such as damage'to the tubes or other component parts of the generator,it isnece'ssary that means be provided to support the tubes againstvibration.

The tube support means should satisfy several criteria. It shouldproperly space and secure tubes relative to each other. It should permitrelative movement between the tubes and the shell in order toaccommodate differential thermal expansion. It should not impair heattransfer between the heating medium and the liquid being vaporized. Itshould not substantially increase the pressure drop on the vaporizablefluid passing through the shell. And additionally, the tube supportmeans cannot be so complex in design or expensive in fabrication as torender it economically infeasible.

The prior art isreplete -.with tube support structures that adequatelyprovide support for straight, vertical tubes or for the vertical legs ofU-tubes arranged in the heat exchanger,

. but such arrangements cannot be successfully adapted. to support thehorizontally extending bend portion of U-shaped tubes. Tube supports forsupporting this portion of a U-tube tube bundle have commonly taken theform of strips or plates SUMMARY OF THE INVENTION The present inventionprovides tube support structure especially adapted for supporting thehorizontally extending bend portion of U-tubes in the tube bundle of ashell and tube-type vapor generator in a mannerthat effects both lateraland vertical support for the tubes and yet permits both longitudinal andcrossflow of fluid through the supported area of the tube bundle. Ingeneral terms,.t he support structure comprises a plurality ofvertically elongated, flat plate members that extend between adjacentlayers of tubes to laterally space the tubes of adjacent tube layersfrom one another. The oppositely spaced vertical edges of the platemembers are provided with recesses disposed in bearing relation betweenadjacent layers of tubes. 5

Such form of support is undesirable for the reason that it progated barsthat extend nonnal to the plates between adjacent tubes in therespective tube rows. The bars are adapted to engage and verticallysupport adjacent tubes on alternate spacing on their upper and lowersurfaces.-

By means of the disclosed tube structure, all of the abovementionedcriteria are satisfied. The tubes are properly spaced and secured withrespect to one another both laterally and vertically. Provision is madefor securing the plates to structural members in ja manner that permitsthermally-induced relative movement between the tube and the enclosingshell to occur. Because the tube support bars are disposed on alternatespacing, crossflow of vaporizable fluid through the region of thesupport structure is permitted, thereby enhancing the transfer of heatbetween the heating medium and the vaporizable fluid as well as reducingthe amount of flow restriction presented by the tube support structureand thus reducing the amount pressure expended by the fluid in flowingthrough the unit as compared with prior art tube support structures. r

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a side elevation of a shelland tube type vapor generator having a tube bundle incorporating thetubesupport structure of the present invention;

FIG. 2 is a partial elevational section taken along line 2-2 of FIG. 1;

FIG. 3 is a partial elevational section taken along line 3-3 of FIG. 2;

. FIG. 4 is a partial elevational section taken along line 4-4 of FIG.1; V, e

FIG. 5 is a partial elevational section taken along line 5-5 of FIG. 4;

FIG. 6 is a plan section taken along line 6-6 of FIG. 1; FIG. 7 isa plansection taken along line 7-7 of FIG. 1; FIG. 8 is a partial plan sectiontaken along line 8-8 of FIG.

FIG. 9 is a partial elevational view of the tube support structure ofthe present invention;

FIG. 10 is a partial elevational view taken along line 10-10 of FIG. 9;

FIG. 11 is a plan sectiontaken along line 11-11 of FIG. 9;

and

FIG. 12 is a partial isometric representation of the tube supportstructure of FIG. 9. l ,1

DESCRIPTION OF-TI-IE PREFERRED EMBODIMENT In FIG. 1 of the drawings,there is shown a shell and tube ,type vapor generator 10 incorporatingthe present invention.

The vapor generator 10 comprises a vertically elongated pressure vesseldefined by: a lower cylindrical shell 12 and a larger diameter, uppercylindrical shell 14 integrally connected with the lower shell by meansof a frustoconical transition member 16. The ends of the vessel areclosed, at the bottom by means of hemispherically formed closure head 18and at the top by a dome-shaped cover 20 containing a vapor outletnozzle 22. The interior of the pressure vessel contains baffle platemembers 24, 26, and 28 that cooperate with the nozzles of the shells toform an inner vessel generation chamber 30 and an outer, annulardowncomer passage 32. At the lower end of the lower shell 12, andintermediate it and closure head 18, is disposed a tube sheet 34 thatextends transversely of the centerline of the vessel and connects withthe wall of the shell. The tube sheet 34 contains a plurality of tubeopenings 36 adapted to fixedly receive the ends of U-shaped heatexchange tubes 38 that form a longitudinally extending tube bundle. 40substantially filling the lower region of the vapor generation chamber30. The tube openings 36 extend through the tube sheet34 to place thetubes 38 in fluid communication with a heating fluid chamber 42 thatoccupies that region of the vessel enclosed between the closure head 18and the tube sheet 34 and which is divided into inlet and outletportions 44 and disposed on alternate spacing and adapted to receiveelon- 46, respectively, by means of a diametrical plate 48. The tubes 38of the tube bundle 40 are arranged such that their opposite endscommunicate, with one of the respective portions of the chamber 42 forthe throughflow of heating fluid through the tubes. The chamber 42 isconnected to a source of heating fluid (not shown) by means of inlet andoutlet nozzles 50 and 52, respectively, that communicate with therespective chamber portions 44 and46 and thereby effect circulation ofheating fluid through thetubes. Feedwater is supplied to the unitthrough an inlet nozzle 54 that is shown penetrating the upper shell 14.A ring header 56 connects with the nozzle 54 and serves to'distributefeedwater passed through the nozzle about the circumference of. thedowncomer passage 32 discharging it into, the passage by means ofdownwardlydirected discharge ports 58 that are spacedly disposed aboutthe lower surface of the header. Flow of the feedwater from thedowncomer passage 32 into the vapor generation chamber 30 is effected bythe spaced relationship that exists between the lower end of the baffleplate 24 and the upper surface of the tube sheet 34.

Within the vapor generation chamber 30 the feedwater is caused to flowin heat exchange relation with the tubes 38 where heat is extracted fromthe heating fluid circulated therethrough to cause some of the feedwaterto be transformed into vapor. The so-created vapor-liquid mixture flowsto the upper region of the vapor generation chamber 30 which .is formedas a mixture collection chamber 60 as defined by the cooperation betweenthe baffle plates 26 and 28. From the mixture collection chamber 60 theflowing mixture is passed to vapor-liquid separator apparatus, amultiplicity of such separators indicated as 62 being mountedupon baffleplate 28 and communicating with the chamber 60 'by means of *openings 63provided in the plate. The separators 62 may be openings 72 throughwhich the leg portions 66 of the tubes 38 are passed. A number of smalldiameter openings 74 are disposed about each of the tube openings 72 andserve to effect longitudinal flow of vaporizable fluid through theplanes of the plates. Vertical support for the plate 70 is provided byappropriate connector means thatattach the plates at circumferentiallyspaced positions about their outer peripheral edges to the inner surfaceof the baffle plate 24. Additional support for these plates may beprovided intermediate their span by at-' tachment to tie rod 76 thatconnect at their lower ends to the tube sheet 34 and which extendlongitudinally of the vapor generation chamber 30 for the principalpurpose of supporting tube support structure attachment plates 112 asdescribed hereinafter.

According to the present invention means are provided to spacedlysupport the laterally extending connecting portion 68 of the U-tubes 38in the upper region of the tube bundle 40. In the arrangementillustrated in FIG. 1 of the drawings, five laterally spaced tubesupport structures indicated as 80 and 80' and constructed according tothe invention are disclosed. It should be understood, however, that agreater or less number of tube support structure can be employed invarious tube bundle applications without departing from the scope of thepresent invention.

Separate designations have been accorded to the tube. support structures80 and 80' herein for the reason that, while the structures both embodyessentially the same structural configuration, as explained hereinafter,different means are employed to anchor the lower ends of the structuredue to the particular region of the tube bundle within which each islocated, the former being in a region wherein the anchor means aresecured by tubes 38 and the latter being disposed in of any well-knownconstruction and are arranged to discharge separated liquid downwardlyupon the baffle plate 28 from whence it is returned to the downcomerpassage 32 to be mixed with the incoming feedwater and recirculatedthrough the unit. The separated vapor, on the other hand, is dischargedfrom the separators in the upward direction and passesthroughappropriate contact drying apparatus 64 from whence it is passedout the vapor outlet nozzle 22 to a point of use. As is common in vaporgenerators of the disclosed type, the U- tubes thatcomprise the tubebundle each include a pair of straight, vertically extending legportions 66 interconnected by a horizontally extending connectingportion 68. In the tube bundle 40 of the unit disclosed herein, thegreat majority of the tubes 38 have connecting portions 68 that aregenerally straight. Those tubes, however, that lie in the innermost tuberows may be formed, asshown, with connecting portions that are generallyarcuate in shape. All of the tubes 38 are small diameter, thin walledtubes that are arranged, as shown in FIG. 2, in closely spaced layerswith each layer containing a plurality of parallel tubes. Inorder toprovide maximum heat transfer effectiveness, the tube layers of thepresent arrangement are disposed such that the tubes therein have theircenters located on a triangular pitch. Such arrangement, as can be seenfrom FIG. '10, places the tubes of each tube layer in alignment withspaces between .the tubes of the adjacent layer, thereby to expose agreater amount of heating surface to the flowing vaporizable fluid.

Because the distance between the secured ends of the tubes 38 in thetube sheet 34 and the top of the tube bundle 40 is of considerablemagnitude as compared with the diameter of the tubes, means must beprovided for spacedly supporting the tubes in order to protc'tthemagainst damage caused by flowinduced and/or mechanically-inducedvibration and also to impart sufficient rigidity to the tubes in orderto maintain their natural spaced relationship in the tube bundle. In thedisclosed arrangement, a plurality of axially spaced horizontallyextending plates 70 are disposed throughout a substantial portion of theheight of the tube bundle 40 and operate to spacedly support thestraight leg portion 66 of tubes 38. These spacer plates 70, being ofwell-known construction, have surfaces that, as shown in FIG. 8, containa plurality of aligned a region that is void of tubes;

The tube support structures 80 and 80' each comprise a plurality ofvertically elongated, thin, flat plate members 82 that are spacedlydisposed in front-to-rear alignment between adjacent layers of tubes 38in the upper region of the tube bundle 40. As shown in FIGS. 2 through5, the plate members 82 that comprise the respective support structures80 or 80' are caused to extend perpendicularly of the connecting portion68 of the U-tubes 38 between upper and lower structural support membersas hereinafter described. The plate members 82 (FIGS. 9 and 12) are eachformed on their oppositely spaced side edges 84 and 86 with :verticallyspaced, rectangular recesses 88, the recesses on the respective edges.being alternately spaced from those on the opposite edge. Thedisposition of the plate members 82 of each support structure 80 or 80'is such as to place corresponding recesses on the plate members inhorizontal front-to-rear alignment thus to sup portingly receive tubespacer bars 90. The spacer bars 90 are horizontally elongated membersthat extend through the tube bundle 40 between adjacent tubes andperpendicular of .the axis of the connection portion 68 thereof. Theupper and lower surfaces of the spacer bars 90 are provided with arcuaterecesses 92 that conform with the exterior of the tube surface 38,thereby to supportingly engage the tubesrand maintain them in mutuallyspaced relation. Because the tubes 38 of the tube bundle 40 in thedescribed embodiment are arranged in a triangular pitch disposition, therecesses 92 on the opposed surfaces of spacer bars 90 are alternatelyspaced. Altematively, were the tubes to be arranged with a square pitch,the recesses 92 on the surfaces of the spacer bars would be disposed inoppositely spaced relation.

As can be seen best from examination of FIG. 12, each 0 the connectingportions 68 of U-tubes 38 as it. passes through tube support structureyet adequate lateral and vertical spacing is provided between the tubesupport members to effect insufficient impedance to longitudinal andcrossflow of vaporizable fluid through this region of the tube bundle.

Each of the tube support structures 80 or 80' is suspendedly mountedwithin the unit by means of mounting assemblies indicated generally inthe respective FIGS. as 94. These assemblies each consist of ahorizontally disposed structural member such as I-beam 96, that extendsacross thewidth of the vapor generation chamber 30 in overlying relationto its associated tube support structure. and having its opposite endsfixedly secured to the inner surface'of the chamber defining plate, hereshown as baffle plate 26, as by means of welding or otherwise. Asuspension plate 98 is slideably securedto the underside of I-beam 96 bymeans of oppositely spaced angle members 100 whose depending legs form aguideway that receives the upper edge of the plate 98. Within the spacedefined by the angle members 100, a slight clearance is provided betweenthe upper end of the suspension plate 98 and the lower flange of beam96. Connection between the plate 98 and anchors 100 is effected by meansof threaded connectors 102 that cooperate with slotted openings '103 inthe plate. In this way any upward expansion of the tube bundle relativeto the mounting assembly, as will occur when the unit is placed inoperation, will be readily accommodated.

Attachment of the tube support structures 80 and 80' to the mountingassembly 94 is effected in the manner shown in FIGS. 2 and 3 wherein, inthe disclosed arrangement, the

suspension plate 98 is formed with the lower end edge 104 having thegeneral configuration of the outline of the upper end of the tube bundle40, and the upper ends of the tube support structure plate members 82are fixedly secured at longitudinally spaced points along the length ofthe edge, as by welding. To facilitate the connection of the platemembers 82 to the suspension plate 98, the upper ends of the former areprovided with a vertical slot 106 (FIG. 9) to receive the lower end ofthe latter. At their lower ends each of the plate members 82 isconnected to horizontally disposed anchor means (attachment plates 112with respect to structures 80 and anchor beam 114 with respect tostructures 80') to preserve the spaced relation between the members atthe bottom of the respective structures. The connections between theplate and anchor members are, however, such as will permit verticalmovement of the tube support structure in response to relative thermalexpansion between the tubes 38 and the mounting assembly 94. Theconnection between the plate members 82 and attachment plate 112 iseffected in the tube support structure indicated as 80 in the mannershown in FIGS. 2, 3, 9, and 10. With reference to the latter FIGS., itcan be seen that the vertical plate members 82 are arranged in pairs andthe lower ends of the plates of each pair are weldedly secured inoppositely spaced relation to the outer surface of a short, hollow,cylindrical sleeve 108. Sleeve 108 is formed with an inside diameterthat enables it to be telescopically disposed over an adjacent tube 38and an outside diameter that permits it to be slideably received in anopening 110 provided in its associated attachment plates 112. Theattachment plates 112 are horizontally disposed plates located in theregion of the tube bundle 40 immediately below the U-tube bend and havea peripheral configuration of chordal sections of a circle (FIG. 7).Vertical support for the respective plates l12 is provided byappropriate attachment means that secure the plates to the inner surfaceof baffle plate 26 and by tie rods 76 that connect with the plates atspaced points adjacent their chordal edge. The surface of the plates 112is similar'to that of the tube support plate 70 having a multiplicity ofaligned tube openings 72 that permit passage'of the leg portions 60 oftubes 38 and smaller diameter openings 74 thereabout to permitlongitudinal flow of vaporizable fluid through the plates. They differ,however, in that the aligned openings IIOthat underIie the tube supportstructures 80 are oversized holes to slidingly receive the structures108 and their enclosed tubes 38.

Connection of the lower end of the tube support structure indicated asdiffers from that of the tube support structure 80. As shown in FIG. 2,the bottom. of the structure 80' is located in a region of the tubebundle 40 that is void of tubes 38. An inverted T-shaped anchor beam 114extends through the tube bundle having its opposite ends secured byappropriate attaching means to the inner surface of the downcomer baffleplate 24. The beam 114 may be supported at longitudinally spaced pointsintermediate its ends by tie rod 76. The upstanding leg 116 of the beam114 is provided along the length of its upper end edge with slots 118adapted to slidingly receive the lower ends of the tube support platemembers 82, the latter having the same general configuration of the tubesupport plate members employed in structures 80, but being provided attheir lower end with slotted edges that are slideably received in theT-beam slots 118.

By means of the novel tube support structure of the present invention,there is provided a simple, inexpensive apparatus operative to spacinglysupport the laterally extending portions of each of the U-tubes thatoccupy the upper region of a tube bundle employed in a vapor generatorof the shell and tube type against the damaging effects of flow-inducedand/or mechanically-induced vibration. Relative vertical movementbetween the tubes is prevented by the opposed disposition of the tubesupport bars between each; vertically spaced tube portion while relativelateral movement between adjacent tubes is prevented by both theinterposed vertical plate members and the tube engaging recesses in thesupport bars. Thermally-induced relative movement between the tubes andthe shell enclosure is accommodated by the floating connection providedbetween the tube support structures and their associated supports. Andfinally, both heat transfer effectiveness and fluid flow efficiency aremaintained at a high degree due to the presence of sufficient flow areathrough the the tube support structure due to the linear displacementexisting between the members of the structure.

It will be understood that various changes in the details, materials,and arrangements of parts which have been herein described andillustrated in order to explain the nature of the invention may be madebythose skilled in the art within the principle and scope of theinvention as expressed in the appended claims.

I claim:

1. In combination, a shell and tube heat exhanger comprisa. asubstantially closed vessel;

b. a bundle of inverted U-tu-bes enclosed by said vessel, said tubesbeing disposed in spaced layers of aligned mutually spaced tubes; i i

c. tube sheet means disposed at one end of said vessel for attaching theends of said tubes;

d. tube support structure for suspendedly supporting the bend portion ofthe tubes in mutually spaced relation including:

1. vertically elongated plate members having laterally spaced side edgesdisposed between each of said tube layers, said plate members beingalignedly arranged along a plane intersecting the planes of said tubelayers,

ii. a row of mutually spaced, horizontally elongated spacer barsarranged along each side edge of said plate members and extendingparallel to the plane of the assembled plate members in interposedrelation between the connecting portions of adjacent tubes in said tubelayers,

iii. means 'for attaching said spacer bars to said plate members; and

e. means for connecting said plate: members in relation to said vesselincluding:

i. structural means disposed above said tube bundle and extendingtranverselyof said vessel in parallel, overlying relation to said tubesupport structure,

ii. means for attaching the opposed ends of said structural members infixed relation to said vessel,

iii. a structure, elongated suspension plate substantially collateralwith said tube support structure, iv. means for attaching the'upper endsof said plate members to said suspension plate, and v. means forexpan'sably connecting said suspension plate to said structural means.2. Apparatus-as recited in claim 1 wherein said tube supportstructureincludes spacer bars in each row having surfaces for engagingthe bend portions of the tubes of each layer on corresponding sidesthereof and the bars of the respective rows 3.. tachment plate means inunderlying relation to said tube support structure; V d. a plurality ofsleeves positioned in said second openings in longitudinal slideablerelation therewith, said sleeves being disposed between the lower endsof alternate plate members of said tube support structure; and e. meansfor fixedly securing each of said sleeves to theadjacent pair of platemembers.

4. Apparatus as recited in claim 3 wherein said sleeves are hollow,cylindrical members and each concentrically encloses the leg portion ofan associated tube of said tube bundle.

5. Apparatus as recited in claim 1 including means for securing thelower ends of said platemembers in spaced relation, said meanscomprising:

a. means forming an attachment beam extending transversely of said vaporgeneration chamber in underlying, parallel relation to said tube supportstructure; and

b. means'forming longitudinally spaced slots in said beam for slideablyreceiving the lower ends of said plate members.

